Jetty embed in Processing.org, static assets + POST - jetty

Question

I'm trying to embed Jetty in a Processing Sketch. So far I made it working to serve static files (a html directory in the Sketch folder).
I want to react to one POST with a user input from one of the static pages.
As I have no knowledge on Jetty and coming from a PHP & Ruby (RoR) web programing background I am very confused with the way things go in Jetty.
I simply want something similar to routes where everything except e.g.
"localhost:8080/post?string=whatever"
is a static file.
The post?string=whatever should maybe trigger a function (in Processing) where the submitted String is handled.
I have been reading the Jetty docs a lot but couldn't figure out so far how to do it.
Thank you very much for any help!
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import java.io.IOException;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.handler.AbstractHandler;
String poststr;
void setup() {
Server server = new Server();
SelectChannelConnector connector = new SelectChannelConnector();
connector.setPort(8080);
server.addConnector(connector);
ResourceHandler resource_handler = new ResourceHandler();
resource_handler.setDirectoriesListed(true);
resource_handler.setWelcomeFiles(new String[] {
"index.html"
}
);
resource_handler.setResourceBase(sketchPath("")+"pftf");
HandlerList handlers = new HandlerList();
handlers.setHandlers(new Handler[] {
resource_handler, new DefaultHandler()
}
);
server.setHandler(handlers);
try {
server.start();
server.join();
}
catch(Exception e) {
};
}

Answer 1

Yes, Jetty can be very confusing in the beginning, especially when you only want to do a couple of simple things (not necessarily full-blown web applications).
The key to making this work is to use a ContextHandler for each of your other handlers (e.g. ResourceHandler). You can tell the ContextHandler which context (i.e. URL) it should respond to. After making a ContextHandler for the ResourceHandler and your custom Handler (e.g. PostHandler) you have to put both in a ContextHandlerCollection (uff...), so your Server knows what contexts exist.
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import java.io.IOException;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.handler.AbstractHandler;
void setup() {
/* Configure the http server */
Server server = new Server();
SelectChannelConnector connector = new SelectChannelConnector();
connector.setPort(8080);
server.addConnector(connector);
/* Resources */
ResourceHandler resourceHandler = new ResourceHandler();
resourceHandler.setDirectoriesListed(true);
resourceHandler.setWelcomeFiles(new String[] {
"index.html"
}
);
resourceHandler.setResourceBase(sketchPath("")+"pftf");
ContextHandler resourceContext = new ContextHandler();
resourceContext.setContextPath("/");
resourceContext.setHandler(resourceHandler);
/* Post API */
PostHandler postHandler = new PostHandler();
ContextHandler postContext = new ContextHandler();
postContext.setContextPath("/post");
postContext.setHandler(postHandler);
ContextHandlerCollection contexts = new ContextHandlerCollection();
contexts.setHandlers(new Handler[] {
resourceContext, postContext
}
);
server.setHandler(contexts);
/* Start the server (finally) */
try {
server.start();
server.join();
}
catch(Exception e) {
println("Could not start http server. Reason: " + e.toString());
};
}
void printCard(String mtext) {
println("Printing card with text: " + mtext);
}
Your PostHandler could look something like this:
public class PostHandler extends AbstractHandler
{
public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
response.setContentType("text/html;charset=utf-8");
String stringParameter = request.getParameter("string");
/* Check if the string parameter is there and not empty */
if (stringParameter != null && !stringParameter.trim().equals("")) {
response.setStatus(HttpServletResponse.SC_OK);
baseRequest.setHandled(true);
response.getWriter().println("<h1>You sent me: " + stringParameter + "</h1>");
println("Received a string via /post: " + stringParameter);
printCard(stringParameter);
}
else {
// Parameter is missing
response.setStatus(HttpServletResponse.SC_BAD_REQUEST );
baseRequest.setHandled(true);
response.getWriter().println("<h1>Error: Missing string parameter</h1>");
println("Missing string via /post.");
}
}
}